Move the signal lever down (for a left turn) or up (for a right turn) to the stop position. The signal will self-cancel after the turn is completed.
If the indicator light continues to flash after a turn, manually return the lever to its original position.

The turn signal indicators in the instrument cluster flash according to the operation of the turn signal lever to show which signal is working.

NOTE
Turn and Lane-Change Signals
Lane-Change Signals and Three-Flash Turn SignalMazda 6 Owners Manual: Tire house trim removal/installation
4SD
1. Remove the rear scuff plate.
2. Remove the rear seat side.
3. Remove the fastener.
4. Pull the tire house trim upward, then disengage clips A from the body, and
remove the tire house trim.
5. Install in the reverse order of removal.
5HB
1. Remove the rear scuff plate.
2. Pull the ...
Mazda 6 Owners Manual: Cargo compartment light switch inspection
1. Remove the liftgate lower trim. (See LIFTGATE LOWER TRIM
REMOVAL/INSTALLATION)
2. Disconnect the cargo compartment light switch connector.
3. Inspect for continuity between the cargo compartment light switch
terminals using an ohmmeter.
If not as specified, replace the liftgate lock.
...